The subject matter disclosed herein relates generally to diagnostic imaging systems, and more particularly to nuclear medicine (NM) imaging systems, especially Single Photon Emission Computed Tomography (SPECT) imaging systems and methods for compensating for motion in an imaged object.
Nuclear medicine (NM) imaging systems, for example, SPECT imaging systems, use several image detectors to acquire imaging data, such as gamma ray or photon imaging data. The image detectors may be gamma cameras or radiation detectors that acquire two-dimensional views of three-dimensional distributions of radionuclides emitted from an object (e.g., a patient) being imaged. The image detectors acquire a plurality of two-dimensional images (also referred to as projections) to create a multi-dimensional image of a structure of interest or photons transmitted from the object. In SPECT systems, 40, 60 or more projections may be acquired, which are then reconstructed to generate a three-dimensional dataset. Backprojection and reconstruction algorithms may then use information about the physical construction and properties of the imaging system to reconstruct the dataset into three-dimensional and/or four-dimensional representations.
In NM imaging, for example, during cardiac SPECT imaging, the heart contracts and relaxes. This motion of the heart is a significant cause of myocardial blurring in reconstructed images. Breathing and other random patient motion (e.g., movement of a hand or arm) also contributes to blurring in the images. Additionally, collimator response causes blurring, which is dependent on the distance from the collimator.
As a result of the blurring of the images, identification of defects, for example, in the radioisotope distribution within the heart are more difficult to identify. As a result of this difficulty, extra diagnostic testing may be needed and misdiagnosis is possible.